• 한국물환경학회지
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• 제23권6호
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• pp.872-880
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• 2007

For effective management of sediment-related diffuse pollution, it is of utmost importance to estimate spatial variation of sediment transport processes within a catchment. A mathematical model can play a critical role in estimating sediment transport processes at the catchment scale provided that the model structure is appropriate for representing major sediment transport processes of the catchment of interest. This paper introduces a distributed catchment model River Basin Water Quality Simulator (RBWQS) and presents some results of its application to a small rural catchment in Korea. The model has been calibrated and validated for a wet period using hourly hydrographs and sediment concentrations observed at the catchment outlet. Based on the model simulation results, the spatial variation of sediment transport processes across the catchment and the effects of paddy fields and small reservoirs on hydrology and sediment transport have been analyzed at the catchment scale.

• 한국환경과학회지
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• 제11권8호
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• pp.793-800
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• 2002

Butyltin (BT) compounds were measured in seawater, sediment, sediment core, settling solids, and plankton from Gwangyang Bay in 2001, Tributyltin (TBT) was detected in seawater from 1 out of the 7 seawater sampling sites and in sediment from 18 out of the 35 sediment sampling sites. The highest concentration of TBT was found in the sediment from the site near Yeosu Harbor (53 ng Sn/g dry wt), acting as the point source for TBT The mean concentrations of TBT were in the order of plankton> settling solids> sediment. The degradation indexes ([DBT]+[MBT]/[TBT]) for the plankton were less than 1, indicating the possibility of recent inputs of TBT. The indexes for the sediment and settling solids ranged from 1.14 to 8.73. The composition of the BT compounds found in the settling solids was similar to that found in the sediment. The vertical profile of the total BT compounds in the sediment was characterized by an abrupt decline from the surface. However, no butyltin compounds appeared below a depth of 10 cm, corresponding to the 1980s. Accordingly, the current results demonstrated that the levels of all butyltin species in the environment of Gwangyang Bay were relatively lower than those in other polluted coastal areas. The vertical profile also suggested a fairly recent history for the down-core.

• 한국물환경학회지
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• 제26권2호
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• pp.215-224
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• 2010

This study was carried out to estimate effects of sediment reduction with net type sediment settling pond at highland agricultural areas. Flow and sediment monitoring system with rainfall gauge were installed at the study area for real-time monitoring and analysis. It was found that amount and intensity of rainfall events strongly affect sediment yield from the study area. With net type sediment settling pond, it was expected that approximately 61% of sediment could be removed. The correlation between heavy metals and SS were analyzed in this study. $R^2$ values were 0.644, 0.876, 0.945, and 0.928 for Fe, Mn, Al, and Si, respectively. This results indicate that heavy metals also could be removed with net type sediment settling pond. As shown in this study, the sediment settling pond will be an efficient sediment reduction facility at highland agricultural areas. For maximum reduction efficiencies of sediment and other pollutants at agricultural fields, simplified sediment settling pond should be designed and implemented.

• 한국물환경학회지
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• 제35권2호
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• pp.105-114
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• 2019

The objective of this study was to investigate the pollution assessment of organic matters, nutrients, and metals in sediment in major lakes (5 lakes and 17 sites) of Buk-han river using various sediment pollution assessment guidelines and indices. The concentrations of organic matters and nutrients were lower than class IV (Sediment pollution assessment guidelines of Korea) and Severe Effect Level (SEL, Sediment pollution assessment guidelines of Ontario). This results indicated that the lakes sediments were unpolluted and tolerable level for sediment dwelling organisms by organic matters and nutrients. However, several sites of Chuncheon and Soyang lakes were evaluated "heavily polluted" level by organic index (Org-index). The order of lakes by metals concentrations from the one with the highest concentration was Hwacheon, Chuncheon, Cheongpyeong, Uiam, Soyang. All lakes except Hwacheon were assessed unpolluted to marginally and tolerable level for sediment dwelling organisms by metals based on sediment pollution assessment guidelines (Korean and Ontario), indices of geoaccumulation ($I_{geo}$), pollution loading (PLI) and ecological risk (RI). In Lake Hwacheon, every investigated sites were polluted with metals, especially Hg, based on sediment pollution assessment guideline of Korea and indices ($I_{geo}$, PLI and RI). The dwelling organisms in sediment of Hwacheon Lake were likely to be severed by metals.

• 한국물환경학회지
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• 제33권6호
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• pp.670-679
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• 2017

An experiment to study the effect of temperature, light, and dredging on release of nutrients downstream from Gongjicheon in the Uiam reservoir was carried out in the laboratory using sediments from different depths. At various water temperatures, dissolved total nitrogen was not released, but the average nutrient flux of dissolved total phosphorus was increased (0.034 at $15^{\circ}C$, 0.005 at $20^{\circ}C$, 0.154 at $25^{\circ}C$, $0.592mg/m^2/d$ at $30^{\circ}C$). Dissolved total phosphorous was released in controlled darkness. In contrast, in controlled light, the concentrations of dissolved total phosphorous and dissolved total nitrogen in the overlying water steadily decreased during the study period (70 d), because they were continuously consumed by the growth of photosynthetic algae. However, there was no significant relationship between water nutrient concentration, nutrient release, and the depth of the sediment. We concluded that the dredging of sediment would not affect the nutrient release rate of the sediment, because there were no significant differences in the nutrient concentrations released from the sediment. When the sediment was removed from the surface to 20 cm in depth, the nutrients were not transferred to the water body, implying that the sediment removal had little effect on secondary pollution.

• 한국해양학회지:바다
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• 제12권4호
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• pp.349-358
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• 2007

투수성이 큰 낙동강 하구 사질 갯벌 퇴적물에서 유기탄소의 생지화학적 순환을 이해하기 위해 현장과 실험실에서 유기탄소 생산 및 소비에 대한 정보를 추정했다. 퇴적물 상부층의 Chl-a 농도와 공극수의 영양염 농도는 니질 퇴적물에 비해 낮았다. 반면, 사질 퇴적물의 산소소모율은 유기물 함량이 높은 연안 니질 퇴적물 보다 높아 이류에 의한 유기탄소의 분해와 물질의 이동이 큰 것을 의미했다. 간단한 유기탄소의 물질수지는 퇴적물에서 유기탄소의 주 공급원이 퇴적물 표층에 서식하는 저서미세조류와 수생식물의 쇄설성 유기물로 나타났다. 해수 여과율에 낙동강 전체 면적을 외삽한 일당 자연 생촉매 여과양은 부산시 7개 주요 하수종말처리장의 최대 처리량 보다 한 자리수 이상 크게 나타나 연안환경에서 사질퇴적물이 생지화학적 정화와 물질의 재분배에 매우 큰 기여를 할 것으로 판단된다.

• 한국물환경학회지
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• 제22권6호
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• pp.1094-1100
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• 2006

In this study, the reservoir sediment reduction methods for long-term operation are proposed by the analysis of both sediment deposit characteristics and sediment reduction effect by each method. To that end, a flowchart for sediment analysis in reservoir is established and sediment deposit is simulated by SMS-SED2D model. The sediment reduction methods which are sediment passing (sluicing), flushing, trapping, bypassing and mechanical removal are used. From the simulation results, the effective method for sediment reduction is operation which is coupled by both sediment passing with sand gate and sediment trapping with debris dam. And If sediment flushing will be used once a year after 50 years, conservation storage can be secured until 100 years after dam construction.

• 한국물환경학회지
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• 제22권6호
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• pp.1088-1093
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• 2006

In this study, the method of annual sediment estimation for reservoir long-term operation is proposed. Long-term daily precipitation and evaporation are predicted by Markov Chain. Using these values, reservoir inflow is simulated by NWS-PC model. Reservoir sediment load is estimated by sediment rating relation curve which is observed. From the simulation results, it was found that each simulated value by Markov Chain and NWS-PC was well compared to the observed ones and also estimated reservoir sediment was appropriate to the compared values using empirical equations. It is thought that the proposed method for estimation of reservoir sediment can be useful used to operate the reservoir.

• 한국물환경학회지
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• 제29권6호
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• pp.799-807
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• 2013

Reservoir sedimentation is one of the major concerns for sustainable reservoir operation. Since sediment concentration of the rivers in the Himalayan Mountain is very high, a proper sediment management scheme is necessary. This paper presents long-term reservoir sedimentation and sediment flushing based on the gate operation. Focused on the reservoir to be constructed for the Patrind hydropower project in Pakistan, 4 different flushing scenarios were proposed in this study to prevent successive sedimentation. By extending flushing period and by increasing the flushing discharge for 2 times, the flushing rate increases up to 53.2% and 43.6% in proportion to flushing period and discharge, respectively. Based on the simulation presented in this paper, it is expected to establish efficient sediment management plan to increase hydro power generation and sediment flushing simultaneously.

• 한국물환경학회지
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• 제29권6호
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• pp.813-824
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• 2013

In this study, sediment pass-through (SPT) from the Sangju Weir and Gumi Weir in the Nakdong River is analyzed numerically using CCHE2D. Sediment delivery is analyzed to predict the sediment discharge rate in the Sangju Weir and Gumi Weir. The sediment discharge from the Sanju Weir is 4,381 tons in the inflow of $3,857m^3/s$, which are 2 year frequency discharge, for 48 hours, and the sediment discharge is 2,766 tons in the inflow of $1,500m^3/s$. The maximum sediment delivery occurs in the immediate downstream of the weir. The sediment discharge from the Gumi Weir is 3,216 tons in the inflow of $5,400m^3/s$, which are 2 year frequency discharge, for 48 hours, and the sediment discharge is 73 tons in the inflow of $3,857m^3/s$. The maximum sediment delivery occurs in the weir. Therefore, the effectiveness of sediment delivery is high in the condition of the 2 year frequency discharge and the gate in the weirs fully are opened.